chore(client): check textarea exists

packages/client/src/components/post-form.vue

@@ -341,8 +341,10 @@ function addTag(tag: string) {
 }
 
 function focus() {
-	textareaEl.focus();
-	textareaEl.setSelectionRange(textareaEl.value.length, textareaEl.value.length);
+	if (textareaEl) {
+		textareaEl.focus();
+		textareaEl.setSelectionRange(textareaEl.value.length, textareaEl.value.length);
+	}
 }
 
 function chooseFileFrom(ev) {